Electrical switch construction with shield

ABSTRACT

An electrical switch construction having a movable switch blade carrying an electrical contact means to be moved into and out of electrical contact with another contact means of the switch construction so as to be adapted to make and break an electrical circuit, a shield being carried by the movable blade to prevent an electrical arc from impinging against a flexure point of the blade as the blade moves the contact means thereof out of contact with the other contact means to break the electrical circuit.

United States Patent Inventor Werner R. Bauer Radnor, Pa.

Appl. No. 801,488

Filed Feb. 24, 1969 Patented Feb. 16, 1971 Assignee Robertshaw ControlsCompany Richmond, Va.

ELECTRICAL SWITCH CONSTRUCTION WITH SHIELD 10 Claims, 3 Drawing Figs.

US. Cl 200/166, 200/67 Int. Cl II0lh 9/30 Field of Search c. 200/67D,146, 16688, 166C [56] References Cited UNITED STATES PATENTS 3.0326275/1962 Ronk ZOO/146(XR) Primary Examiner-H. 0. Jones A!t0rneys- AuzvilleJackson, Jr., Robert L. Marben and Candor, Candor & Tassone ABSTRACT: Anelectrical switch construction having a movable switch blade carrying anelectrical contact means to be moved into and out of electrical contactwith another contact means of the switch construction so as to beadapted to make and break an electrical circuit, a shield being carriedby the movable blade to prevent an electrical are from impinging againsta flexure point of the blade as the blade moves the contact meansthereof out of contact with the other contact means to break theelectrical circuit.

ELECTRICAL SWITCH CONSTRUCTION WITI-I SHIELD This invention relates toan improved electrical switch construction and to a method for makingsuch a switch construc- I tion or the like.

It is well known from the copending Pat. application Ser. No. 674,186,filed Oct. 10, 1967, that relatively small electrical switchconstructions can be made wherein an electrical contact means is carriedby a snap blade to be moved into and out of contact with a stationarycontact of the switch construction.

However, it has been found, according to the teachings of thisinvention, that such small switch construction is not readily adaptableto overcome an arcing' problem that exists when the movable contactmeans is moved away from the fixed contact means to break the electricalcircuit through the switch construction because such electrical arcingimpinges against a flexure point 'of the snap blade and therebysubsequently causes the blade to fracture or break at the flexure pointthereof after a certain time period of use of the switch construction.

It has also been found according to the teachings of this invention thatif such prior known snap-acting blade is made larger or thicker towithstand the heat being applied thereto by the aforementioned arcing,not only is the cost of such switch construction increased, but also theaccuracy thereof is diminished.

Therefore, it is a feature of this invention to provide means forpreventing the aforementioned electrical arcing from adversely affectingsuch a snap blade or the like.

In particular, one embodiment of this invention provides a metal shieldthat is carried by'the movable blade and is so constructed and arrangedthat the same prevents the electrical are from impinging against theblade as the blade moves the contact means thereof out of contact withthe other contact means to break the electrical circuit, the shieldcomprising a generally L-shaped metal member having one of the legsthereof attached to the blade by the contact means thereof so as to bestacked between the contact means and the blade and having the other legthereof angularly disposed relative to the blade to redirect theaforementioned electrical arc away from the flexure point of the switchblade.

Accordingly, it is an object of this invention to provide an improvedelectrical switch construction having one or more of the novel featuresset forth above or hereinafter shown or described.

Another object of this inventionis to provide an improved method formaking such a switch construction or the like, the method of thisinvention having one or more of the novel fea- 5 tures set forth aboveor hereinafter shown or described.

Other objects, uses and advantages of this invention are ap-v parentupon a reading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIG. 1 is a cross-sectional view of the improved switch construction ofthis invention;

FIG. 2 is a view similar to FIG. I and illustrates the switchconstruction in another operating position thereof;

FIG. 3 is a top view of the switch blade of the switch construction ofFIG. 1 w ith the protective shield being superimposed thereon in itsassembled position.

While the various features of this invention are hereinafter describedand illustrated as being particularly adapted to provide electrical arcredirecting means for a snap switch construction of miniature size, itis to be understood that the various features of this invention can beutilized singly or in any combination thereof to provide-improvements inother types of electrical switches as desired.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to FIGS. 1 and 2, the improved electrical switchconstruction of this invention is generally indicated by the referencenumeral 10 and comprises the basic switch structure fully disclosed andclaimed in the aforementioned copending patent application whereby thevarious details thereof will now be described in only sufficient detailto understand the present invention as the copending patent applicationcan be referred to for a further description of the specific details andoperation of the switch construction 10.

The switch construction 10 comprises a housing means 11 carrying threeterminals 12, 13, and 14 projecting therefrom with the inner ends 15 and16 of the terminals 12 and 13 being disposed within a chamber 17 formedin the housing means 11 and defining spaced fixed contact means of theswitch construction 10. The other terminal 14 comprises a pivot postmeans 18 disposed within the chamber 17 and having opposed notches 19and 20 therein respectively to receive bowed tongues 21 and 22 of aswitch blade 23 having one end 24 thereof bearing against one leg of aU-shaped leaf spring 25 on one side thereof and against a movableplunger means 26 on the other side thereof. Since the switch'blade 23 iselectrically conductive, the engagement of the tongues 21 and 22 thereofwith the post 18 electrically connects the blade 23 to the terminal 14.

The movable plunger means 26 has a portion 27 projecting out of anopeningr28 inthe housing means 11 so that when the plunger portion 27 ispushed inwardly from the normal position illustrated in FIG. 1, to theposition illustrated in FIG. 2 in opposition to the force of the leafspring 25, the switch blade 23 snaps downwardly from the position ofFIG. 1 to the position of FIG. 2 and when the pushbutton 27 is releasedto permit the spring 25 to move the end 24 of the blade 23 upwardly backto the position in FIG. 1, the blade 23 automatically snaps from theposition illustrated in FIG. 2 back to the position illustrated in FIG.1.

The switch blade 23 carries an electrical contact means 29 on theleft-hand end 30 thereof which is normally held in electrical contactwith the fixed contact 15 to complete an electrical circuit between theterminals 12 and 14 as illustrated in FIG. 1 and when the plunger 27 isdepressed downwardly as il- 0 lustrated in FIG. 2, the switch blade 23snaps the movable contact 29 thereof out of electrical contact with thefixed contact l5 and into electrical contact with the fixed contactmeans 16 as illustrated in FIG. 2 to complete an electrical circuitbetween the terminals 13 and 14, if desired.

However, as previously mentioned, it has been found that when the bladecontact 29 breaks away from the fixed contact 15 to terminate theelectrical circuit between the terminals 12 and 14, electrical arcingtakes place with such arcing tending to impinge against a flexure line31, FIG. 3, formed in the switch blade 23 that permits the tongue 21 ofthe blade 23 to bow so that the subsequent repeated heating of theflexure point or area 31 of the blade 23 by the opening and closingaction of the switch 10 causes the tongue 21 to fracture or break at theflexure point 31, thereby preventing long life for the switchconstruction 10. v 7

However, according to the teachings of this invention, an areredirecting shield 32 is provided and comprises a metal member formed insubstantially'an-L-shape so that one leg or portion 33 thereof isdisposed against the upper side of the left-hand end 30 of the blade 23and has an opening 34 passing therethrough in aligned relation with asimilar opening 35 in the end 30 of the blade 23 whereby a part 36 ofthe contact means 29 can pass through the aligned openings 34 and 35 ofthe shield '33 and blade 23 and be secured against the other side of theblade 23. In this manner, the shield 32 is secured to the blade 23 instacked relation between the movable contact means 29 and the end 30 ofthe blade 23. The other leg or portion 36 of the shield 32 is angularlydisposed relative to the portion 33 thereof and extends upwardly fromthe blade 23 as illustrated in FIGS. 1 and 2 so as to face toward thefixed contact 15 whereby when the blade 23 snaps from the positionillustrated in FIG. 1 to the position illustrated in FIG. 2, the shield32 will be impinged by the electrical arcing taking place during thebreaking of the movable contact 29 away from the contact so as toredirect such arc away from the flexure point 31 of the switchblade 23whereby the flexure point 31 of the switchblade 23 will not be subjectedto impingement by 'such arcing to heat the same that causes theaforementioned deterioration in the flexure area 31.

In this manner, the shield 32 has been found to extend the life of theswitchblade 23 without requiring an enlargement or thickening of theparts of the switchblade 23 which would add greatly to the cost thereofas well as to the accuracy of operation of the switch construction 10,particularly when the switch construction 10 is made of subminiaturesize.

In the embodiment of the shield 32 illustrated in the drawings, the sameis made of the same width as the switchblade 23 and is formed ofantimagnetic material, such as stainless steel or the like. Any arcingthat occurs at the contacts during operation in a circuit sets up anelectromagnetic field. The shield 32, when made of antimagneticmaterial, will not interact with the electromagnetic field to influencethe movement of the switchblade 23.

Further, in one embodiment of the shield 32 of this invention, the legor portion 33 thereof had a length of approximately 0.07, plus or minus0.002, ofan inch, the leg or portion 36 thereof had a length ofapproximately 0.035, plus or minus 0.002, of an inch, the shield 32 hada thickness of approximately 0.0015 of an inch and the largest width ofthe shield 32 was approximately 0.120, plus or minus 0.002, of an inch.

Accordingly, it can be seen that this invention not only provides animproved electrical switch construction, but also this inventionprovides an improved method for making such a switch construction toeliminate an adverse electrical arcing problem thereof.

I claim:

1. In an electrical switch construction having a movable switch bladecarrying electrical contact means to be moved into and out of electricalcontact with another contact means of said switch construction so as tobe adapted to make and break an electrical circuit, the improvementcomprising a shield carried by said blade to prevent an electrical arefrom impinging against said blade as said blade moves said contact meansthereof out of contact with said other contact means to break saidelectrical circuit, said shield disposed between said other contactmeans and said blade.

2. In an electrical switch construction as set forth in claim 1, thefurther improvement wherein said blade has a flexure area that isshielded from said are by said shield.

3. In an electrical switch construction as set forth in claim 2, thefurther improvement wherein said shield is L-shaped and has one ofthelegs thereof secured to said blade.

4. In an electrical switch construction having a movable switch bladecarrying electrical contact means to be moved into and out of electricalcontact with another contact means of said switch construction so as tobe adapted to make and break an electrical circuit, the improvementcomprising a shield carried by said blade to prevent an electrical arefrom impinging against said blade as said blade moves said contact meansthereof out of contact with said other contact means to break saidelectrical circuit, said shield is secured to said blade by said contactmeans. I

5. In an electrical switch construction having a movable switch bladecarrying electrical contact means to be moved into and out of electricalcontact-with another contact means of said switch construction so as tobe adapted to make and break an electrical circuit, the improvementcomprising a shield carried by said blade to prevent an electrical arefrom impinging against said blade as said blade moves said contact meansthereof out of contact with said other contact means to break saidelectrical circuit, said blade having an opening therein receiving partof said contact means securing said contact means thereto said shieldhaving a portion thereof provided with an opening aligned with saidblade opening and receiving part of said contact means whereby saidshield is secured to said blade by said contact means in stackedrelation between said contact means and said blade.

6. In an electrical switch construction as set forth in claim 5,

the further improvement wherein said shield has another portion thereofangularly disposed relative to said first-named portion thereof andextending away from said blade in a direction to face toward said othercontact means.

7. In an electrical switch construction as set forth in claim 6, thefurther improvement wherein at least one of said portions of said shieldhas a width substantially the same as the width of said blade.

8. In an electrical switch construction as set forth in claim 7, thefurther improvement wherein the remainder of said shield has a widthsubstantially the same as the width of said blade.

9. In an electrical switch construction having a movable switch bladecarrying electrical contact means to be moved into and out of electricalcontact with another contact means of said switch construction so as tobe adapted to make and break an electrical circuit, the improvementcomprising a shield carried by said blade to prevent an electrical arcfrom impinging against said blade as said blade moves said contact meansthereof out of contact with said other contact means to break saidelectrical circuit, said shield is formed from antimagnetic material.

10. In an electrical switch construction as set forth in claim 1, thefurther improvement wherein said blade is snap-acting.

1. In an electrical switch construction having a movable switch bladecarrying electrical contact means to be moved into and out of electricalcontact with another contact means of said switch construction so as tobe adapted to make and break an electrical circuit, the improvementcomprising a shield carried by said blade to prevent an electrical arcfrom impinging against said blade as said blade moves said contact meansthereof out of contact with said other contact means to break saidelectrical circuit, said shield disposed between said other contactmeans and said blade.
 2. In an electrical switch construction as setforth in claim 1, the further improvement wherein said blade has aflexure area that is shielded from said arc by said shield.
 3. In anelectrical switch construction as set forth in claim 2, the furtherimprovement wherein said shield is L-shaped and has one of the legsthereof securEd to said blade.
 4. In an electrical switch constructionhaving a movable switch blade carrying electrical contact means to bemoved into and out of electrical contact with another contact means ofsaid switch construction so as to be adapted to make and break anelectrical circuit, the improvement comprising a shield carried by saidblade to prevent an electrical arc from impinging against said blade assaid blade moves said contact means thereof out of contact with saidother contact means to break said electrical circuit, said shield issecured to said blade by said contact means.
 5. In an electrical switchconstruction having a movable switch blade carrying electrical contactmeans to be moved into and out of electrical contact with anothercontact means of said switch construction so as to be adapted to makeand break an electrical circuit, the improvement comprising a shieldcarried by said blade to prevent an electrical arc from impingingagainst said blade as said blade moves said contact means thereof out ofcontact with said other contact means to break said electrical circuit,said blade having an opening therein receiving part of said contactmeans securing said contact means thereto, said shield having a portionthereof provided with an opening aligned with said blade opening andreceiving part of said contact means whereby said shield is secured tosaid blade by said contact means in stacked relation between saidcontact means and said blade.
 6. In an electrical switch construction asset forth in claim 5, the further improvement wherein said shield hasanother portion thereof angularly disposed relative to said first-namedportion thereof and extending away from said blade in a direction toface toward said other contact means.
 7. In an electrical switchconstruction as set forth in claim 6, the further improvement wherein atleast one of said portions of said shield has a width substantially thesame as the width of said blade.
 8. In an electrical switch constructionas set forth in claim 7, the further improvement wherein the remainderof said shield has a width substantially the same as the width of saidblade.
 9. In an electrical switch construction having a movable switchblade carrying electrical contact means to be moved into and out ofelectrical contact with another contact means of said switchconstruction so as to be adapted to make and break an electricalcircuit, the improvement comprising a shield carried by said blade toprevent an electrical arc from impinging against said blade as saidblade moves said contact means thereof out of contact with said othercontact means to break said electrical circuit, said shield is formedfrom antimagnetic material.
 10. In an electrical switch construction asset forth in claim 1, the further improvement wherein said blade issnap-acting.